The constituents of the universe are often found in clusters of objects,
in planetary systems and in galaxies. The galaxies with stars were
established shortly after the ”Big Bang" [1]}.
The two groupings of objects have a common feature, the objects rotate
around their center of gravity. But a rotating galaxy
seems, however, to be unstable unless it contains a significantly larger
mass (dark matter) than given by the known baryonic matter in the galaxy [2]}.
